The present invention relates to improvements in transverse connectors for use in making connections between two spinal rods that are placed along a patient's spine during spinal osteosynthesis procedures.
Surgically implanted spinal osteosynthesis apparatus often includes a pair of rods which are secured along at least a portion of the spine on opposite sides thereof by a system of hooks, bone screws including sacral screws and pedicle screws and transverse connectors for the purpose of stabilizing and adjusting spinal alignment.
Although in a preferred system the spinal rods would be in parallel alignment, the rods are seldom parallel in practice. Placement of the rods in a skewed alignment is often necessary to produce the desired corrective or supporting forces on the spine. In practice the rods may be co-planar but not parallel or may be non co-planar. In some instances the rods are non co-planar and transversely divergent. Each of these non parallel configurations produces difficulty with respect to the joining of connectors to the rods, since rod receiving heads of the connectors are most stable when they join perpendicular with respect to the rods. If the rods themselves are not parallel, the connectors cannot form the most stable juncture with the rod, if the connectors are straight and cannot be bent to the most suitable configuration for joining. In addition the location of spinal processes sometimes requires that a connector have an arch that is adjustable to just clear the spinal process such that the connector does not protrude further rearward of the spine than is necessary. Preferred transverse connection systems will readily permit variations in the alignment of the rods while providing fast securement resistant to slipping or dislocation.